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cull out most of the SVD calculation when stress is low

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Xuchen Han
2019-10-29 22:35:44 -07:00
parent 959a48a1a0
commit 6dce8e4ff5
1 changed files with 21 additions and 15 deletions
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36
src/BulletSoftBody/btDeformableNeoHookeanForce.h
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@@ -176,24 +176,30 @@ public:
btMatrix3x3 P;
firstPiola(psb->m_tetraScratches[j],P);
#if USE_SVD
btMatrix3x3 U, V;
btVector3 sigma;
singularValueDecomposition(P, U, sigma, V);
if (max_p > 0)
{
sigma[0] = btMin(sigma[0], max_p);
sigma[1] = btMin(sigma[1], max_p);
sigma[2] = btMin(sigma[2], max_p);
sigma[0] = btMax(sigma[0], -max_p);
sigma[1] = btMax(sigma[1], -max_p);
sigma[2] = btMax(sigma[2], -max_p);
// since we want to clamp the principal stress to max_p, we only need to
// calculate SVD when sigma_0^2 + sigma_1^2 + sigma_2^2 > max_p * max_p
btScalar trPTP = (P[0].length2() + P[1].length2() + P[2].length2());
if (trPTP > max_p * max_p)
{
btMatrix3x3 U, V;
btVector3 sigma;
singularValueDecomposition(P, U, sigma, V);
sigma[0] = btMin(sigma[0], max_p);
sigma[1] = btMin(sigma[1], max_p);
sigma[2] = btMin(sigma[2], max_p);
sigma[0] = btMax(sigma[0], -max_p);
sigma[1] = btMax(sigma[1], -max_p);
sigma[2] = btMax(sigma[2], -max_p);
btMatrix3x3 Sigma;
Sigma.setIdentity();
Sigma[0][0] = sigma[0];
Sigma[1][1] = sigma[1];
Sigma[2][2] = sigma[2];
P = U * Sigma * V.transpose();
}
}
btMatrix3x3 Sigma;
Sigma.setIdentity();
Sigma[0][0] = sigma[0];
Sigma[1][1] = sigma[1];
Sigma[2][2] = sigma[2];
P = U * Sigma * V.transpose();
#endif
// btVector3 force_on_node0 = P * (tetra.m_Dm_inverse.transpose()*grad_N_hat_1st_col);
btMatrix3x3 force_on_node123 = P * tetra.m_Dm_inverse.transpose();